Worldwide interoperability for microwave access (WiMAX) is a wireless metropolitan area network (MAN) access technology that basically aims to provide an interoperable broadband wireless access means in a point-to-multipoint (PTM) multi-vendor environment in an MAN.
Existing standards specify that an air interface protocol layer of a WiMAX system mainly includes a physical (PHY) layer and a medium access control (MAC) layer. The PHY layer physically performs operations such as modulation, demodulation, encoding, and decoding of signals. The MAC layer mainly performs a MAC function of the WiMAX system.
FIG. 1 shows an end-to-end reference model of a WiMAX system, in which an RI interface is a wireless air interface and other interfaces are all wired interfaces.
Referring to FIG. 1, the WiMAX system mainly includes a mobile station (MS)/user station (SS), an access service network (ASN), and a connectivity service network (CSN).
The ASN is defined as a set of network functions that provide wireless access services to WiMAX user terminals, and includes a base station (BS) and an ASN gateway (ASN-GW). One ASN may be shared by a plurality of CSNs.
The CSN is defined to provide IP connectivity services to the WiMAX user terminals.
The MS/SS is a (mobile) terminal, with which a user accesses the WiMAX network.
Many of multimedia services require a plurality of users to concurrently receive the same data, such as video on demand, television broadcast, video conferencing, online education, and interactive gaming. Currently, the services may be realized through an Internet Protocol (IP) multicast and broadcast technology in the wired network. However, if the services are implanted to the mobile network, the services have large data amount and long duration, and are delay sensitive as compared with the common data, and the mobile network has special network structures, function entities, radio interfaces, etc., so the existing IP multicast and broadcast technology cannot be applied to the mobile network directly.
In order to effectively use the mobile network resources, the WiMAX defines a multicast broadcast service (MBS). The MBS is a point to multipoint (PTM) service in which one data source is provided in the mobile network to send data to multiple users, so as to realize shared network resources and improve the utilization of the network resources, especially the air interface resources. The MBS defined by the WiMAX not only implements the multicast and broadcast of pure text messages at a low rate, but also implements the multicast and broadcast of high-rate multimedia services, which undoubtedly conforms to the development trend of the mobile data services.
The MBS based on the WiMAX network supports two access modes, namely, single-BS access and multi-BS access. In the multi-BS access mode, the concept of an MBS zone (identified by an MBS zone ID) is defined, which is a set of BSs. All BSs in one MBS zone use the same Multicast CID and MBS Group Security Association (MBS GSA) ID, and send the contents of the same MBS flow. The terminal that has registered the MBS may receive the data of the MBS through multiple BSs in the MBS zone. When a terminal in an idle mode moves from one BS to another BS in the MBS zone, the terminal does not need to reestablish a connection, and can receive the MBS without being affected, which realizes the seamless handoff of the MBS. The single-BS access to MBS is a particular case of the multi-BS access to MBS. In this case, MBS zones are defined within the coverage of a BS, and all users in one MBS zone that receive the MBS use the same Multicast CID. In the prior art, the single-BS mode is not described in detail, but corresponding descriptions about how a BS sends MBS data, how a terminal receives the MBS data, and how the BS notifies the terminal that the MBS data of interest has been sent in the multi-BS mode can be found.
In existing protocols, the air interface in the MBS system has been described; the technology describing how to a terminal joins the MBS is not available.